Metabolic cold adaptation in insects: A large-scale perspective
1. Despite its significance from both life-history and physiological perspectives, metabolic cold adaptation (MCA) in insects remains controversial. Although several smallscale studies have provided support for such adaptation, many others have not. 2. Using a global-scale analysis of the standard metabolic rates of 346 species, it is shown that after removing the effects of trial temperature and body mass, environmental temperature significantly influences interspecific variation in metabolic rate, such that insects from colder environments tend to have higher, whole-organism, metabolic rates. Although this effect is weak, it does provide evidence in favour of MCA in this important terrestrial group. 3. Although data from the Southern Hemisphere are limited, we show that this adaptation also takes the form of an increase in the slope of the metabolic rate-temperature relationship in Northern, but not in Southern, Hemisphere species. 4. Metabolic cold adaptation and its variation among the hemispheres should be counted among the causes of interspecific variation in metabolic rate.